U.S. patent number 4,596,935 [Application Number 06/601,646] was granted by the patent office on 1986-06-24 for device for the production and reflection of infrared or ultraviolet radiation.
Invention is credited to Christian Lumpp.
United States Patent |
4,596,935 |
Lumpp |
June 24, 1986 |
**Please see images for:
( Certificate of Correction ) ** |
Device for the production and reflection of infrared or ultraviolet
radiation
Abstract
The invention relates to a panel for the production and
directional reflection of infrared or ultraviolet radiation. The
quartz tubes (5) employed for emission of radiation are juxtaposed
within a frame. The rear reflector is constituted by V-section
elements (8) which are placed side by side in order to define
reflecting troughs (19). Application: construction of a
self-supporting reflector which permits variation in power, outputs
and wavelengths of the infrared-radiation emitted by the panel.
Inventors: |
Lumpp; Christian (88560 Saint
Maurice sur Moselle, FR) |
Family
ID: |
27251158 |
Appl.
No.: |
06/601,646 |
Filed: |
April 18, 1984 |
Foreign Application Priority Data
|
|
|
|
|
Apr 25, 1983 [FR] |
|
|
83 07082 |
Nov 8, 1983 [FR] |
|
|
83 18063 |
Nov 8, 1983 [FR] |
|
|
83 18066 |
|
Current U.S.
Class: |
250/495.1;
392/411; 392/424; 250/504R |
Current CPC
Class: |
F21V
7/005 (20130101); F26B 3/30 (20130101); F24C
15/22 (20130101); F24C 1/10 (20130101) |
Current International
Class: |
F24C
1/00 (20060101); F24C 1/10 (20060101); F26B
3/30 (20060101); F26B 3/00 (20060101); F21V
7/00 (20060101); F24C 15/22 (20060101); F24C
15/00 (20060101); G01J 001/00 () |
Field of
Search: |
;250/493.1,494.1,495.1,54R ;350/614,628 ;126/439 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Anderson; Bruce C.
Attorney, Agent or Firm: Felfe & Lynch
Claims
I claim:
1. Device for the production and reflection of infra-red radiation
in the form of a panel in which a plurality of radiation-emitting
tubes are grouped together and reflecting means are located behind
said tubes, wherein said device comprises
a rectangular frame in which the said radiation-emitting tubes are
placed at an equal distance and parallel to each other parallel to
a longitudinal direction,
said reflecting means comprising a reflector having concave troughs
behind said emitting tubes,
each of said troughs being formed by a juxtaposed assembly of two
symmetrical longitudinal elements having a V-shaped cross-section
with two externally concave arms having end portions with flanges,
a longitudinal reflecting shield supported by said frame and
masking a connecting gap formed by two juxtaposed elements,
said longitudinal elements at two opposite ends and said frame
comprising cooperating means, said cooperating means including
slots for receiving said end portions of said concave arms while
said flanges extend laterally out of said slots, said cooperating
means retaining said elements and permitting thermal expansion in
use.
2. Device in accordance with claim 1, characterized in that each
longitudinal element having a biconcave V-section is constituted by
a sheet metal member which is bent to said V-section profile so
that said element is not only self-supporting but also capable of
elastic deformation under the action of variable thermal stresses
of the type encountered, for example, if the radiant power and
therefore the wavelength of the rays emitted by the quartz tube are
varied during operation.
3. Device in accordance with claims 1, characterized in that each
V-section element has two externally concave lateral faces, each
face being surmounted by a flange which is in turn surmounted by a
ledge which is bent inward to a slight extend so that when several
elements are juxtaposed, a longitudinal gap is thus defined between
each flange of one element and the adjacent flange of the adjacent
element.
4. Device according to claim 1, characterized in that each
reflector comprises a juxtaposed assembly of rear shields and of
elements in the form of two half-troughs, and at least the elements
in the form of two half-troughs are hollow, a coolant fluid being
circulated within the internal space pf said elements.
5. Device in accordance with claim 1, characterized in that the
rear shields are also hollow and have a double wall, a coolant
fluid being circulated within the internal space of said
shields.
6. Device in accordance with claim 1, characterized in that the
coolant fluid which circulates within the double walls of the
reflector is blown air.
7. Device in accordance with claim 1, characterized in that each
element in the form of two half-troughs is constructed by
interengaging two identical members which are formed of sheet metal
bent to a cross-section having a V-shape with inwardly curved wings
each surmounted by a vertical flange and the assembly operation
being performed by means of a weld fillet for joining together the
flanges and and by means of weld fillet for joining together the
flanges and.
8. Device in accordance with claim 4, characterized in that each
rear shield is constructed by interengaging two identical members
of sheet metal bent to a cross-section having the shape of a
circular arc surmounted by two vertical end flanges, the assembly
operation being performed by means of a weld fillet for joining
together the flanges and by means of a weld fillet for joining
together the flanges.
9. Device in accordance with claim 4,
characterized in that each element in the form of two half-troughs
is constructed by bending a strip of sheet metal completely closed
by a longitudinal weld fillet and having a triangular
cross-section, two sides of which are curvilinear and joined
together by two rectilinear flanges.
10. Device in accordance with claim 4, characterized in that each
rear shield is constructed by bending a strip of sheet metal
completely closed by a longitudinal weld fillet and having a
cross-section in the shape of a circular arc joined by means of two
vertical flanges to the flat top wall.
11. Device in accordance with claim 1, characterized in that at
least the reflecting surface of each V-section element of the
reflector is constituted by a layer or a sheet of gold or of
another reflecting metal.
12. Device in accordance with claim 1, for providing a barrier to
the radiation emitted by a tube in the direction of a gap defined
in the reflector with is located being said tube, characterized in
that the shield is constituted by an opaque strip applied along
part of the rear surface of the radiant tube which is either of
metal or ceramic material.
13. Device in accordance with claim 12, characterized in that the
opaque strip forming the shield is constituted by a metallization
deposit formed directly on the wall of the tube, provision being
accordingly made for an ordinary tube which is metallized only
along a reflectorized strip.
14. Device in accordance with claim 12, characterized in that the
shield is constituted by a concave sheet-metal strip mounted
against a portion of the rear longitudinal wall of the tube.
15. Device in accordance with claim 12, characterized in that the
width of the metallic strip in the form of a trough is distinctly
smaller that the diameter of the tube.
16. Device in accordance with claim 12, characterized in that the
concave metal trough constituting the shield is fixed on the tube
by snap-action engagement of a resilient fastening-clip, with the
result that when a tube is changed, the shield of the old tube can
be used on the new tube.
17. Device in accordance with claim 12, characterized in that
detachable fastening of the metallic strip is effected by means of
resilient clips.
18. Infrared-radiation tube for equipping a device in accordance
with claim 12, characterized in that provision is made along the
lenght of said tube for an opaque strip of metal or ceramic
material having a width which is smaller than the diameter of said
tube.
19. Device in accordance with claim 12, characterized in that the
shield is constituted by a concave opaque strip of sheet metal
fitted with hook-type fastening clips which can be engaged by
hooking over flanges formed at the top edges of the two
half-troughs, and the shield being accordingly maintained at a
distance between the emitting tube and the gap which is masked by
the shield without interrupting the circulation of air.
20. Device in accordance with claim 19, characterized in that each
hook-type fastening clip is provided with a tubular spacer member a
connecting-screw and a resilient fastening strip.
21. Device in accordance with claim 19, characterized in that the
panel is constituted by a frame formed by two cross-members and by
two longitudinal members and the emitting tubes being placed side
by side in parallel relation to the cross-members.
22. Device in accordance with claim 19, characterized in that a
longitudinal slot is provided in each vertical flange at each end
of a V-section section element.
23. Device in accordance with claim 19, characterized in that each
shield is constituted by a simple strip of sheet metal which is
cambered so as to have a concave cross-section and is consequently
also self-supporting after said strip has been placed in a position
in which it covers the rear portion of the corresponding
longitudinal gap.
24. Device in accordance with claim 19, characterized in that the
juxtaposed assembly of V-section elements defines around each
quartz tube a longitudinal reflecting the top of which forms a
longitudinal connection gap whose width is capable of varying
during operation.
25. Device in accordance with claim 19, characterized in that a
horizontal flange is provided along the longitudinal member while
an opposite longitudinal flange is provided along the longitudinal
member, the slots of one end of each V-section element being
engaged over the flange of the longitudinal member whereas the
slots formed at the opposite end of said element are engaged over
the flange of the longitudinal member.
26. Device in accordance with claim 19, characterized in that two
contiguous troughs of the panel are separated only by a
longitudinal arris having a practically zero width.
Description
The present invention relates to a device for the production and
diffusion by reflection of infrared or ultraviolet radiation.
Devices of this type are already known which are constructed in the
form of panels and can be employed, for example, in the paper
industry, the textile industry, the plastics industry, and so on.
Infrared-radiation panels are also employed in tunnel furnaces for
such purposes as baking of bread in industrial bakeries or
paint-drying in the automobile industry.
In the majority of cases, infrared radiation is produced by
rectilinear quartz tubes disposed at intervals and in parallel
relation over the entire surface of the panel, the rear face of
which is occupied by a reflector system designed to reflect all the
emitted radiation toward the front. The structure of the panel and
more particularly the construction of the reflector set a problem
which is difficult to solve for the following essential
reasons:
the reflector and its supporting members are subjected to high
thermal stresses as a result of the high temperature of the quartz
tubes located in the immediate vicinity;
these stresses vary with the radiant power of the quartz tubes;
it is difficult to construct a reflector which withstands these
high and variable stresses while entirely occupying the large area
of the panel.
In French Pat. No. 70 21350 has been proposed a lighting device
including a grid for the distribution of light, comprising
lengthwise reflection blades the upper part of which ending at the
lamp side, as intermediary reflecting blades having nearly the
shape of a V.
This device is related to lighting as such and does not concern
infrared radiations. Furthermore, the opening angle corresponding
to lost radiation is 110.degree., what represents 30% of the whole
radiation and no ventilation is foreseen. Such a structure could
not be used at temperatures of about 2700.degree. K. that is to say
the temperature of the devices according to the present
invention.
In U.S. Pat. No. 3,654,471 has been described a reflector device
for electromagnetic radiation from an elongated radiation source
comprising a profiled holder formed as a body having a cavity that
provides a supporting surface for a reflecting metal strip.
In such structures, a blade of air is formed between two reflecting
devices and induces the creation of venturi phenomenon bringing
corrosive vapors into contact with the lamp and the reflecting part
of the device.
It is found in practice that the majority of known installations
solve the problem incompletely. For example, it is known to
construct a panel which is capable of diffusing only infrared
radiation of constant wavelength. This is attended by a
disadvantage in practice since it is known that the possibility of
varying the wavelength during operation would be advantageous, all
the more so as a short infrared quartz tube is much more costly
than a long infrared tube.
The object of the present invention is to overcome these drawbacks
by providing a device for the production and reflection of infrared
radiation, in the form of a panel in which a plurality of
radiation-emitting tubes are grouped together and in which
reflecting means are located behind said tubes. The distinctive
feature of the invention lies in the fact that the tubes are placed
at an equal distance and parallel to each other within a
rectangular frame while a reflector in the general form of a series
of concave troughs is located behind the emitting tubes. Each
trough is placed behind one tube and is defined by a juxtaposed
assembly of two longitudinal elements each having a V-shaped
cross-section with two externally concave arms. The connecting gap
formed between two juxtaposed elements is masked by a longitudinal
shield placed at this location behind the two elements, each of
which is self-supporting.
In accordance with another distinctive feature of the invention,
each longitudinal element having a concave V-section is constituted
by a sheet metal member which is bent to said V-shaped
cross-section. In consequence, said longitudinal element is not
only self-supporting but is also capable of elastic deformation
under the action of variable thermal stresses of the type
encountered, for example, if the radiant power and therefore the
wavelength of the emitted rays are varied during operation.
In order to improve the performances of this device, more
particularly when the infrared-radiation has a high intensity, it
is useful to forsee a reflector for infrared-radiation emitting
tubes in accordance with the invention comprising a juxtaposed
assembly of rear shields and or elements in the form of two
half-troughs and distinguished by the fact that at least the
elements in the form of two half-troughs are hollow, a coolant
fluid being circulated within the internal space of said
elements.
In accordance with another distinctive feature of the invention,
the rear shields are also hollow and have a double wall, a coolant
fluid being circulated within the internal space of said
shields.
The coolant fluid which circulates within the double walls of the
reflector may be, for example, blown air.
A number of different technological solutions may be proposed for
constructing the double wall of the shields and of the V-section
elements consisting of two half-troughs.
An improvement has also been foreseen in order to position more
easily the protective shield at the level of each junction gap
between each of the two half-troughs.
The shield device in accordance with the invention for providing a
barrier to the radiation emitted by a tube in the direction of a
gap defined in the reflector which is located behind said tube is
distinguished by the fact that the shield is constituted by an
opaque strip applied along part of the rear surface of the radiant
tube.
In accordance with another distinctive feature of the invention,
the metallic strip forming the shield is constituted by a
metallization deposit formed directly on the wall of the tube,
provision being accordingly made for an ordinary tube which is
opacified only along a reflectorized strip of metal or of ceramic
material.
In accordance with yet another distinctive feature of the
invention, the shield is constituted by a concave sheet-metal strip
mounted against a portion of the rear longitudinal wall of the
tube. In other words, the width of said metallic strip in the form
of a trough is distinctly smaller than the diameter of the tube. It
should be clearly understood that the term "metal" is used in its
broadest sense, that is to say without any limitation with regard
to the nature of the metal employed.
In accordance with a further distinctive feature of the invention,
the concave metal trough constituting the shield is fixed on the
tube by snap-action engagement of a resilient fastening-clip, with
the result that, when a tube is changed, the shield of the old tube
can be used on the new tube.
Finally, according to a particular mode of realization of the
invention each V-section element of the reflector is constituted at
least at its reflecting surface by a layer of sheet of gold or
other metals.
It must be said that for simplifications purposes, the invention
herein described will only refer to devices for the production of
infrared-radiations, but it will be understood that these devices
may be used for any radiation and more particularly for
ultra-violet radiation.
Other features of the invention will be more apparent upon
consideration of the following description and accompanying
drawings, wherein:
FIG. 1 is a front view of an emitting and reflecting panel in
accordance with the invention;
FIG. 2 is a part-sectional view of the panel taken along line
II--II (FIG. 1);
FIG. 3 is a perpective view showing one of the V-section elements,
the justaposed assembly of which forms the reflector;
FIG. 4 is a perspective view showing one of the shields which is
placed behind the connection gap of the V-section elements of the
reflector;
FIG. 5 is a transverse sectional view taken along line V--V (FIG.
1) and showing the arrangement of the reflector as a whole and of
the emitting tubes.
FIG. 6 shows two members prior to assembly for the construction of
a double-wall element having a curvilinear V-section;
FIG. 7 shows the element which has thus been completed;
FIGS. 8 and 9 are two similar views for the construction of a rear
shield with a double wall;
FIGS. 10 and 11 correspond to another alternative form of
construction of the V-section element and the rear shield;
FIG. 12 is a transverse sectional view of the reflector which is
obtained by means of the alternative embodiment of FIGS. 6 to
9;
FIG. 13 is a similar sectional view of the receiver which is
obtained by assembling the members of the alternative embodiment of
FIGS. 10 and 11;
FIG. 14 is a sectional view illustrating a known form of
construction for positioning the shield;
FIG. 15 is a corresponding view which illustrates the device in
accordance with the invention;
FIG. 16 shows an infrared-radiation tube in accordance with the
invention;
FIGS. 17 to 19 illustrate two alternative embodiments of a
detachable shield in accordance with the invention.
There is shown in the drawings a panel 1 which is employed both for
producing infrared-radiation and for diffusing said radiation by
reflection over its entire surface.
The panel consists of a frame formed by two cross-members 2 and by
two longitudinal members 3 and 4. Emitting tubes 5 of quartz are
placed side by side and in parallel relation on the rectangular
frame thus formed. Each tube 5 is placed within the frame and
parallel to the cross-members 2, one end of each tube 5 being
supported by the longitudinal member 4 while the other end is
supported by the longitudinal member 3. This latter is also
provided with electrical connection means consisting in particular
of terminal connectors 6 for supplying current to the quartz tubes
5.
The tubes 5 are disposed at intervals on the front face of the
panel 1, the rear face of which is occupied by a reflector 7. The
entire reflector is formed by the juxtaposed assembly of V-section
elements 8 and rear shields 9 (FIG. 5).
Each V-section element 8 is constituted by a sheet metal member
bent to a V-shaped cross-section having externally concave lateral
faces 10 and 11. Each lateral face 10 or 11 of the V is surmounted
by a flange 12 or 13 and this latter is in turn surmounted by a
ledge 14 or 15 which is bent inward to a slight extent. There is
thus obtained a structure which is shown in detail in FIG. 3 and
has the advantage of being self-supporting while at the same time
permitting the free development of expansion stresses and
deformation even if these latter are variable in time as it is the
case if it is desired to vary during operation the power and
wavelength of the emitted infrared-radiation.
In order to facilitate the assembly, each flange 21 and 23 is
preferably provided with a longitudinal slot 16 for each end of the
vertical flanges 12 and 13.
Each shield 9 is constituted by a simple strip of sheet metal which
is cambered so as to have an arcuate cross-section, with the result
that said strip is also self-supporting. The width 17 of each
shield 9 is greater than or equal to the distance 18 between the
divergent ends of two ledges 14 and 15 which are juxtaposed after
assembly (FIG. 5).
In a best mode of realization (not shown on the drawings) the
holder of V-section elements 8 is formed by simple pins which hold
the ends of the ledges 14, 15. For the shields 9, three pins are
foreseen, one at the center of the concave part, and two at the
ends of the convex part.
The juxtaposed assembly of V-section elements 8 and shields 9 for
the purpose of forming the rear reflector of the panel 1 in
accordance with the invention takes place as shown in FIG. 5. In
other words, the V-section elements 8 are placed longitudinally and
side by side, each vertical flange 12 of one element being located
in the immediate vicinity of the vertical flange 13 of the adjacent
element. There is thus defined around each quartz tube 5 a
longitudinal reflecting trough 19, the top of which has a
longitudinal connecting gap 20. This gap corresponds to the
distance between two adjacent flanges 12 and 13 and its width can
vary during operation as a function of progressive variations in
power and consequently in temperature. In order to avoid any loss
of radiation toward the rear of the reflector, which would in any
case correspond to accidental overheating in this zone, the rear
side of each gap 20 is closed by covering it with a longitudinal
shield 9 which is placed in the manner illustrated in FIGS. 2 and
5. By virtue of the arrangement, it is ensured that the entire
radiation emitted by each tube 5 in all directions is reflected
toward the front of the panel 1.
For the purpose of assembly, the longitudinal member 4 preferably
has a U-shaped cross-section and the bottom flange 21 of said
member is adapted to engage in the slots 16 formed in the
corresponding end of each V-section element 8. Similarly, each
longitudinal member 3 has a U-section member 22, the bottom
horizontal flange 23 of which is provided with slots 16 for the
corresponding end of each V-section element 8. It is apparent that,
after assembly of the frame 2, 3, 4 the ends of the juxtaposed
V-section elements 8 are each engaged between the flanges 21 and 23
in such a manner as to ensure that this engagement permits the free
development of variable expansion deformations.
Each electrical connection terminal 6 is preferably constituted by
a metal connecting stud 24 fitted in a horizontal bearing flange 25
of the longitudinal member 3 with interposition of sleeves 26 of
insulating material. The lower metallic end of each stud 24 is
connected to a bracket 27 which has the function of supplying
current to the quartz tube 5 while at the same time supporting the
corresponding end of this latter.
The shields 9 which cover two juxtaposed inwardly bent ledges 14
and 15 (FIGS. 2 and 5) are preferably held in position by
engagement beneath the top flange 28 or 29 of the corresponding
U-section member 4 or 22.
As will readily be apparent, the transverse profile of each
reflecting trough 19 can correspond to any adapted mathematical
shape, especially a circular, elliptical or parabolic shape. Better
still, two adjacent reflecting troughs can be separated to a
greater or lesser extent by increasing the width of the gap 20,
thus making it possible to vary the general shape of the reflecting
section of the trough 19. By way of example, this can permit the
use of two juxtaposed incandescent filaments within one or two
quartz tubes 5 placed side by side. In each case, the width 18 of
the shield 9 is calculated accordingly in order to provide a total
barrier to rearward radiation through the gap 20.
Finally, it is worthy to note that two contiguous troughs 19 are
separated from each other only by an arris 30 of zero width. No
width is therefore lost between the troughs 19, thus increasing the
radiant power of the entire device in respect of the same overall
size of the panel 1 and making it possible to fit a greater number
of quartz tubes 5 in said panel.
As it has been hereabove explained, it is possible to make better
the performances of the device, among others when the
infrared-radiations have a high intensity.
There is shown in FIGS. 6, 7 and 12 a reflector element in the form
of two half-troughs and constructed by assembling together two
elementary members 31 and 32.
The member 31 is formed of sheet metal bent to a V-shaped
cross-section having two curvilinear arms 33 and 34 each surmounted
by a vertical flange designated respectively by the references 35
and 36.
The member 32 has a cross-section which is identical with that of
the member 31 (FIG. 6).
In order to carry out the assemb1y, the member 31 is tightly fitted
within the member 32, thus producing an elastic deformation in
order to engage the flanges 35 and 36 of the member 31 between the
flanges 45 and 46 of the member 32. The amplitude of this
deformation corresponds to the thickness 37 of the sheet metal of
each of these members. The engagement of one of the members 31 and
32 within the other is not performed to a complete extent in order
to leave between said members a gap 38 corresponding to a double
wall which extends over the full length of the curved wings of the
V-section.
In order to complete the assembly, there is deposited on each said
a weld fillet or bead 39 which joins together the flanges 35 and
45, and a weld fillet 40 for joining together the flanges 36 and
46.
Similarly, the rear shield of the reflector is defined by
interengagement of two members 41 and 42 which are identical with
each other. The member 41 is of sheet metal bent to a cross-section
in the shape of a circular arc 43 which is raised at each end so as
to form two flanges 47 and 48.
The member 42 also has a cross-section in the shape of a circular
arc 44 located beween two flanges 49 and 50.
In order to construct th shield 41, 42 of FIG. 8, the member 41 is
force-fitted between the flanges 49 and 50 of the member 42. This
movement is carried out with an ampliitude of elastic deformation
which corresponds to the thickness of the sheet metal. Engagement
is not carried out completely in order to leave a free gap 51
between the two circular arcs 43 and 44 (FIG. 12).
In this case also, the assembly operation is performed by placing a
weld fillet 52 along the flanges 47 and 49 while a similar weld
fillet 53 assembles the flanges 48 and 50.
In the alternative ambodiment illustated in FIGS. 10 to 13, each
element in the form of two half-troughs 54 is constructed in a
single piece in the form of a strip of bent sheet metal, the
cross-section of which defines as in the previous embodiment the
two inwardly curved wings 33 and 34 of a V and the two lateral
flanges 35 and 36. In this case, however, these two flanges are
each surmounted by a longitudinal ledge 35, 36. These two ledges
are bent toward each other and overlap in their connection zone in
which they are joined together by means of a weld fillet 57. The
reflector element 54 is therefore provided in the form of a tube
whose transverse cross-section has substantially the shape of a
triangle, two sides of which are curvilinear.
Similarly, each shield 58 of said reflector is formed by
folding-bank a single strip of sheet metal with a cross-section
comprising a circular arc 44 located between two bent-back flanges
49 and 50 having extensions in the form of two longitudinal ledges
59 and 60 which are bent-back toward each other until they overlap
in their connection zone. In this zone, a weld fillet 51 completes
the assembly.
The operation is as follows:
In the heating appliance, one zone of the reflector is located
behind each infrared-radiation emitting tube 61 and comprises:
two elements in the form of half-troughs and designated by the
references 31, 32 (alternative embodiment of FIG. 12) or by the
reference 54 (alternative embodiment of FIG. 13);
a rear shield designated by the reference 41, 42 in FIG. 12 and
designated by the reference 58 in FIG. 3.
It is known that these reflector elements are sufficient to protect
the rear zone of the appliance (the top of each FIGS. 12 or 13
against any accidental loss or leakage of infrared-radiation in
this direction.
In the case of the present invention, since each element 31, 32,
41, 42 or 54, 58 of the reflector is of double wall construction,
it has an internal space 38, 51 or 62, 63 in which is circulated a
coolant fluid such as, for example, air or even water.
By virtue of this arrangement, the heating power of the tubes 61
can be considerably increased while maintaining the reflector as a
whole at a relatively low temperature. Among other things, this
protects the rear zone of the reflector against any accidental
overheating.
As hereinabove indicated, the presence of a gap between to
reflecting devices is liable to produce both a loss of
infrared-radiation and overheating of the rear zone of the cassette
at the bottom of each trough, that is to say behind each generating
tube.
In order to overcome these drawbacks, it is possible to foresee a
rear shield as shown on FIGS. 14 to 19.
There is shown in FIG. 14 a portion of a cassette of a known type
employed as an infrared-radiation generator.
Said cassette comprises in particular radiation-emitting tubes 71
each located opposite to a reflecting trough 72. The reflector
assembly as a whole is constituted by a juxtaposed array of a
plurality of reflecting elements 3 each having a cross-section in
the shape of a V, the two wings of which are concave. The pointed
tip of the V of each element 73 defines a longitudinal arris 74.
Thus each trough 72 is defined between two successive arrises 74
formed by two half-troughs 75 and 76 corresponding to two different
elements 73. The junction between the two half-troughs 75 and 76 is
effected at the bottom of the trough 72 along a longitudinal gap
77.
In order to prevent the radiation emitted by the tube 71 from being
lost by diffusion through the gap 77 to the rear zone 78 of the
cassette, it is possible to place in position a shield 79
consisting of a shallow trough having high rigidity. It is apparent
from FIG. 14 that the positioning of the shields 79 complicates the
manufacture of the entire cassette to a considerable extent by
reason of the fact that:
in the first place, a well-defined free space 80 must be left
between the shield 79 and the gap 77 in order to avoid any
interference with the flow of cooling air;
in the second place, this arrangement makes it necessary to provide
a shield 79 of relatively substantial width 81 which is much larger
than the width of the gap 77.
In accordance with the invention (FIGS. 15 to 17), a shield of this
type is no longer provided behind the gap 77. This gap 77 still
remains shielded against radiations by means of a shield 82 but the
invention lies in the fact that the shield 82 is located in front
of the gap 77.
In the embodiment illustrated in FIGS. 15 and 16, the shield 82 is
constituted by a narrow strip of metal or ceramic material which is
deposited directly on the wall of the emitting tube 83. In other
words, each emitting tube 83 in accordance with the invention is
accordingly provided with its own shield 82 as shown in the form of
a narrow metallic strip disposed longitudinally on the wall of the
tube.
In the alternative embodiment illustrated in FIGS. 15 and 17, the
metallic strip 82 constituting the shield is designed on the
contrary in the form of a detachable strip, that is to say a narrow
strip of sheet metal which can be attached to the tube 83 by
slightly forcible engagement of resilient snap-action clips 84.
In the alternative embodiment illustrated in FIGS. 18 and 19, the
back of the metallic strip 82 constituting the shield is fitted
with hook-type fastening-clips 85 each formed by a tubular spacer
member 86, a screw 87, and a cross-strip 88 which can be detachably
engaged over the flanges 89 (FIG. 18) by hooking, said flanges 89
being formed along the top edge of two half-troughs 75 and 76 on
each side of the gap 77. Thus, after assembly (FIG. 18), the shield
82 is fixed between the tube 71 and the gap 77 so as to mask this
latter while permitting free circulation of air.
* * * * *